The lunar module design underwent gradual evolution from the first configuration proposed by Grumman in 1962. This model is the 1964 version. Langley had the task of building a simulator for the astronauts to practice lunar landings. The configuration of the initial vehicle used with the Lunar Landing Research Facility (LLRF) was changed in 1967 to more accurately reflect the standing position of the astronauts, cockpit arrangement, instrumentation, controls and field of view.